Hey Scotty, my grandfather has a 94 f150 with an automatic transmission. The engine has about 375k miles on it. When I start it up it idles at around 2000rpm, in neutral it stays at high rpms also. However once I put it in drive or reverse it stays at a settle 750rpm. If I want to go into reverse I have to put it in drive and then put it in reverse, if I just go straight to reverse from park it does a horrible jerk. As I get it on road while its cold, in between 2 and 3rd gear it downshifts, it does it even more so if the ac is on so this gives me an idea that its electronic, and does the jerk in between 2 and 3rd gear. However after the truck is warmed up everything is normal. We have been dealing with this for a few years now, even hauling over maximum payload for hauling wood but we have to try and baby it when we haul. We think its a torque converter. However I want your answer on what it could be. Thank you.